The carcinogenic process is the result of accumulation of molecular damage to DNA, including activation of protooncogenes and mutation or deletion of tumor suppressor genes. Detection of the early alterations which may be present in various types of cancer could serve as sensitive biomarkers to facilitate early diagnosis of the disease. One of the most consistent and frequent genetic lesions in carcinogenesis is the activation mutation of the first base of codon 12 of the K-ras onconogene. An assay capable of detecting low levels of K-ras mutations could be used in the clinic for earlier diagnosis of premalignant changes. the ligase chain reaction (LCR) is a sensitive methodology which has only recently been utilized to detect human K-ras mutations. The specific aims of this project are to: (1) adapt assay to non-isotopic methods, (2) increase the number of reactions possible per analysis by using microtiter plates for the LCR, and (3) develop mulitiplexing analysis to simultaneously determine other sites of K-ras mutations. Technical innovations would be introduced to develop a screening assay or kit which would be introduced to develop a screening assay or kit which would be affordable, easy to perform and interpret, and rapid. Such an assay could provide significant health and economic benefits and have widespread commercial application. PROPOSED COMMERCIAL APPLICATIONS: The potential commercial application of Phase I and II of this project is the development of a non-isotopic assay using PCR-based LCR methodology to determine the K-ras status of human DNA samples. The procedure must be (1) accurate, (2) easy to perform and interpret, (3) sensitive, (4) rapid and (5) amenable to large scale screening.